Clutch drag on my 51 ES2

..shimming the springs til you get an even throw-out at the pressure plate. It will help some. Driving it for awhile will bed in the friction plates and take the high spots off also helping.

I would say that clutch drag was an accepted norm  on most brit bikes  but that the scarcity of traffic meant that it was not a big problem in days gone by. Some makes did better with dry clutches sealed in housings (my Rudge does not drag.)  With extra attention to detail  and quality parts (!) a good clutch can be achieved but it may take some time and experimentation .( only took me 24 years , a new center ,spider ,plates ,special rollers and a Dial gauge).Making the clutch pull lighter was another whole saga .

On the upright and lay down boxes when the clutch is operated, the thrust is taken by the bronze thrust washer between the mainshaft and high gear. This can cause the rear wheel to turn  on the stand. Release the clutch and the wheel may slow or remain stationary when brakes are applied. The AMC box is different because the thrust is absorbed by the right hand mainshaft bearing.

The acid test is finding neutral from first with the engine running. If yes, all is good. If you can't, stop the engine, and retry. If you can then find neutral, the clutch is dragging. 

What you are experiencing is the main shaft of the gearbox spinning inside the output shaft and tending to turn the output shaft and hence the rear wheel. It's pretty normal and in a way is a good sign that your wheel has little drag. The clutch is fully engaged so can't be dragging. 

Clutch drag is when you have the bike in gear with clutch disengaged and you struggle to find neutral or in extreme cases the bike tries to move. 

Personally I wouldn't be concerned by what you're experiencing. 

Hi Grant

It doesn't sound like clutch drag at all to me, it's gearbox drag!  The clutch cannot be dragging if you're in neutral as you say because the clutch is fully engaged and spinning with the engine.

Clutch drag is when the bike tries to inch forwards when in gear with the clutch pulled in, or when coming to a standstill and you can't get neutral.

If you're expecting the rear wheel to stop spinning when on the stand, in neutral with the clutch pulled in, I think that's a big ask! The true test is out on the road.

.. Ian and Bob said. Perfectly normal, and not clutch drag at all.

Of course it is possible that the clutch does drag but that would have different symptoms. Come back when you've tried riding it. Did you replace the bronze thrust washer and the associated roller retaining washer when you rebuilt the box as these are common causes of clutch drag?

ps the clutch screws need to all be tightened down fully. Unlike other clutches, the pressure plate is forced to lift square as it is lifted by the mushroom headed thrust pin.

My quick test for clutch drag is to put the bike in gear with the engine running and try to paddle it backwards. It shouldn't really be any or much harder than if it is in neutral.

... you didn't change the thrust washer it's worth checking for end float on the main shaft. When the washer and its associated roller washer wear it means that you lose quite a lot of motion in the clutch operating mechanism as the first part of movement is just taken up by closing up the clearance.

... isn’t it!  and what a nice bike.  Looks very original and complete.  Amazing how they still turn up so unmolested. Enjoy it.

Cheers

Jon